Therapeutic Drug Monitoring Flashcards
Therapeutic drug monitoring is defined as…
“a process of assessing concentration of a drug in biological fluids such that it is maintained within the therapeutic range.”
Therapeutic drug monitoring aims at…
…individualizing the dose for a patient to obtain maximum benefit.
Therapeutic drug monitoring (TDM) is generally defined as the clinical…
…laboratory measurement of a chemical parameter that, with appropriate medical interpretation, will directly influence drug prescribing procedures.
TDM involves the use of drug concentration…
…measurements in body fluids as an aid to the management of drug therapy for the cure, alleviation or prevention of disease.
The main focus of TDM is…
…drugs with a narrow therapeutic range i.e. drugs that can easily be under- or overdosed.
TDM is based on the principle that…
…for some drugs, there is a close relationship between the plasma level of the drug and its clinical effect.
The clinical value of plasma level monitoring depends on…
…how precisely the treatment outcome can be defined
The therapeutic range/ therapeutic window is…
… the concentration range of drug in plasma where the drug has been shown to be efficacious without causing toxic effects in most people.
Therapeutic Index (TI) refers to…
…the ratio of the dose of drug that causes adverse effects at an incidence/severity not compatible with the targeted indication (e.g. toxic dose in 50% of subjects, TD50) to the dose that leads to the desired pharmacological effect (e.g. efficacious dose in 50% of subjects, ED50).
In a drug development setting, TI is calculated based on…
…plasma exposure levels
Therapeutic index = LD50 x ED50. True or false?
False. It’s division, not multiplication
Criteria for TDM in drugs
- Unpredictable relationship between dose and plasma
- Narrow therapeutic window
- Steep dose response curve
- Difficult-to-measure therapeutic/toxic evidence
- Saturable metabolism
- Poorly defined endpoint/response
Features of drugs with narrow therapeutic window
They allow dosage alterations to produce optimal therapeutic effect
TDM is not useful in…
- Drugs having wide therapeutic index
- Where toxicity is not a realistic concern
- Effects can be measured using functional laboratory tests
- Plasma concentration not predictably related to effects
- Hit and run drugs
Components of an optimum TDM service
- Timely measurement of patient’s serum or plasma drug concentration
- Knowledge of pharmacological and pharmacokinetic profiles of the drugs
- Knowledge of relevant patient’s profile
- Interpretation of SDC after taking into consideration all of the above information
Processes involved in TDM
- Development of plasma profile
- Clinical effect of drug
- Development of dosage regimen
- Diagnosis, dosage form selection, dosage regimen, initiation of therapy
- Evaluation of clicinical response